This invention relates to a protocol conversion apparatus and protocol conversion method for selecting a protocol for data transmitted between a plurality of terminals to be the most suitable protocol at each terminal or a network, and performing adjusting operation between protocols of each terminal.
FIG. 16 shows an applied connection example of a conventional protocol conversion apparatus disclosed in the Unexamined Japanese Patent Publication 11-127216. FIG. 17 shows an internal configuration of the conventional protocol conversion apparatus. FIG. 18 is a flowchart showing operations performed by the conventional protocol conversion apparatus.
In FIG. 16, the following are shown: a terminal A 10 connected to a closed area network, a terminal B 20 connected to a public network, a protocol conversion apparatus 30 which connects the terminals A and B by converting protocols when necessary, a closed area network 40 for connecting the terminal A and the protocol conversion apparatus, and a public network 50 for connecting the terminal B and the protocol conversion apparatus.
In FIG. 17, the following are shown: a control unit 100 for controlling the protocol conversion apparatus, and for sending and receiving control signals to/from the terminals, and a closed area network interface unit 110 for interfacing with the closed area network. The closed area network interface unit 110 sends/receives main data to/from a switching unit in the apparatus, and sends/receives control signals for the terminals to/from the control unit. A public network interface unit 120 for interfacing with the public network is also shown. The public network interface unit 120 sends/receives main data to/from the switching unit in the apparatus, and sends/receives control signals for the terminals to/from the control unit. A switching unit 130 for connecting cards for a transmission of main data, a control signal 200 from the terminal A or the closed area network, a control signal 210 from the terminal B or the public network, a main data signal 220 transmitted between the terminal A and the terminal B, and a protocol conversion unit 310 for converting PCM speech data of 64 Kbps to compressed speech data of 8 Kbps are also shown in FIG. 17.
Now, operations will be explained. With reference to FIGS. 16 and 17, it is supposed that the terminal B 20 transmits signals and the terminal A 10 receives the signals. The control signal 210 indicating a transmission of signals from the terminal B 20 is input into the public network interface unit 120 of the protocol conversion apparatus 30, and the information is forwarded to the control unit 100 from the public network interface unit 120. The control unit 100 analyzes the contents of the control signal 210 and detects the type of a bearer required to be used for transmission.
When the bearer requested by the terminal B 20 is non-restricted digital data of 64 Kbps, the control unit controls the switching unit 130 in order to establish a path for the main data 220 on a non-restricted digital bearer of 64 Kbps between the public network interface unit 120 and the closed area network interface unit 110.
On the other hand, if the bearer requested by the terminal B 20 is speech, the control unit directs the switching unit 130 and a suitable protocol conversion unit 310 to set up a path for the main data 220 through the public network interface unit 120, the protocol conversion unit 310, and the closed area network interface unit 110.
In this case, the protocol conversion unit 30 performs a mutual conversion between the PCM speech signal of 64 Kbps and the compressed speech signal of 8 Kbps. Thus, the PCM speech signal of 64 Kbps can be transmitted between the terminal B 20 and the protocol conversion apparatus 310, and the compressed speech signal of 8 Kbps can be transmitted between the protocol conversion apparatus 30 and the terminal A 10.
In the case of an image terminal, a FAX, a MODEM, or others, only a basic bearer is selected based on the control signal at the sending/receiving time, and after the bearer is connected, the connectivity between the terminals is confirmed based on a protocol between the terminals. Then, the protocol which has been confirmed of providing mutual connectivity is used for communications.
However, in the conventional protocol conversion apparatus, the protocol requested by the terminal is judged based only on the contents of control signals from the terminal or the network. It is only possible to judge a basic point, such as whether data output from the terminal is digital data or speech data, based on the contents of the control signals. Therefore, only a conversion for a basic bearer can be performed in the conventional protocol conversion apparatus. Thus, it has been impossible to perform the most suitable protocol conversion.
For instance, when image terminals respectively using different protocols are to be connected, it is just possible to judge that data is non-restricted digital data of 64 Kbps based on the control signal, in the conventional protocol conversion apparatus. Then, at the sequence of confirming the connectivity between the image terminals to be performed later, the protocol which can be used in both the terminals is selected, or the communications is disconnected by the terminals if the connectivity is not confirmed. In usual cases, the best function which the terminal can perform may mostly be limited in the protocol which can be used for both the terminals.
It is one of objects of the present invention to solve the above problem, and it is another object to elicit the function of each terminal as much as possible and to perform the most suitable protocol conversion.
According to one aspect of protocol conversion apparatus of the present invention, the protocol conversion apparatus, connected to a calling side terminal and a called side terminal, for performing protocol conversion between the calling side terminal and the called side terminal, comprises:
a protocol conversion unit for performing protocol conversion between a calling side protocol of the calling side terminal and a called side protocol of the called side terminal;
a signal detect unit for detecting a connectivity confirmation signal transmitted between the calling side terminal and the called side terminal; and
a control unit for specifying the calling side protocol and the called side protocol based on the connectivity confirmation signal detected by the signal detect unit;
wherein the protocol conversion unit can perform protocol conversions of plural types,
wherein the control unit selects one protocol conversion out of the protocol conversions of plural types performed by the protocol conversion unit, based on a specified calling side protocol and a specified called side protocol, and
wherein the protocol conversion unit performs the protocol conversion selected by the control unit.
According to another aspect of protocol conversion apparatus of the present invention, the protocol conversion apparatus, connected to a calling side terminal and a called side terminal, for performing protocol conversion between the calling side terminal and the called side terminal,
the protocol conversion apparatus further connected to a protocol conversion software database storing a plurality of protocol conversion software of plural types corresponding to protocol conversion types, the protocol conversion apparatus comprises:
a protocol conversion unit for performing protocol conversion between a calling side protocol of the calling side terminal and a called side protocol of the called side terminal;
a signal detect unit for detecting a connectivity confirmation signal transmitted between the calling side terminal and the called side terminal; and
a control unit for specifying the calling side protocol and the called side protocol based on the connectivity confirmation signal detected by the signal detect unit;
wherein the control unit selects one protocol conversion software out of the plurality of protocol conversion software of plural types based on a specified calling side protocol and a specified called side protocol, and gives the protocol conversion unit directions to download a selected protocol conversion software, and
wherein the protocol conversion unit downloads the selected protocol conversion software based on the directions of the control unit.
According to another aspect of protocol conversion apparatus of the present invention, the signal detect unit detects the connectivity confirmation signal by monitoring a main data signal transmitted between the calling side terminal and the called side terminal.
According to another aspect of protocol conversion apparatus of the present invention, the control unit sets up a line between the protocol conversion unit and the called side terminal, based on the connectivity confirmation signal detected by the signal detect unit.
According to another aspect of protocol conversion apparatus of the present invention, the control unit has made the protocol conversion unit be ready for starting before the signal detect unit detects the connectivity confirmation signal.
According to another aspect of protocol conversion apparatus of the present invention, the signal detect unit is included in the protocol conversion unit.
According to another aspect of protocol conversion apparatus of the present invention, the signal detect unit detects H221/H242 or H223/H245 based on ITU-T Recommendation used as the connectivity confirmation signal for image data communication.
According to another aspect of protocol conversion apparatus of the present invention, the signal detect unit detects one of T30, V34, and V90 based on ITU-T Recommendation used as the connectivity confirmation signal for FAX/MODEM communication.
According to one aspect of protocol conversion method of the present invention, the protocol conversion method, for performing protocol conversion between a calling side terminal and a called side terminal, comprises the steps of:
detecting a connectivity confirmation signal transmitted between the calling side terminal and the called side terminal;
specifying a calling side protocol and a called side protocol based on the connectivity confirmation signal detected in the detecting step; and
performing protocol conversion between the calling side protocol of the calling side terminal and the called side protocol of the called side terminal;
wherein the performing protocol conversion step can perform protocol conversions of plural types,
wherein the specifying the calling side protocol and the called side protocol step selects one protocol conversion out of the protocol conversions of plural types performed in the performing protocol conversion step, based on a specified calling side protocol and a specified called side protocol, and
wherein the performing protocol conversion step performs protocol conversion selected in the specifying the calling side protocol and the called side protocol step.